Below are PDF scans of the response calibration charts for a pair of DPA 4061 miniature omnis, matched by DPA back in 2003. These are actual measured response graphs, rather than the more generic, idealized response curve found on DPA's website and provided with all 406x microphones. This measurements reflect the ~ +5dB response boost at 9kHz imparted by the low-boost short-grid installed on the microphones.

"low-boot"? Are these the default soft-boost grids which are stated to give +3dB boost at 15k?

So what is the deal with the idealized response graphs DPA is showing on their site? Their marketing department overruling their engineers?

In my head-baffled stage lip / stack recordings, I've often felt the high frequencies sound overemphasized even with EQ to undo the boosts based on the idealized graphs. I figured sound engineers at shows were assuming everybody was wearing earplugs and boosted the highs to compensate.

Thanks Volt. I knew that thread was somewhere but didn't find it with a quick search. I'll link this one there as well.

Hi dabbler- Thanks for catching that typo. Yes, low-boost grids. DPA doesn't specify the response with those grids specifically at 15kHz, but specifies the response this way (quoted from their website):

The graphs I posted above of these two specific microphones fall within that specified tolerance. Unlike their more costly lines of microphones, DPA does not normally provide individually measured response graphs specific to each serial number for the miniatures. I don't think any manufacturer of miniature microphones does that. The generic response graph and polar chart on their website and in the pamphlet which is provided with the microphones is the average "idealized" response from which any specific mic may vary by ± 2 dB. So take that as the base-line from which the response of any one mic may vary by ± 2 dB , yet still be within the stated tolerance range.

The response of these two specific mics varies by less than 1dB from each other, and only at a couple narrow points, rather than over a broader range, which indicates quite good matching.

my head-baffled stage lip / stack recordings, I've often felt the high frequencies sound overemphasized even with EQ to undo the boosts based on the idealized graphs. I figured sound engineers at shows were assuming everybody was wearing earplugs and boosted the highs to compensate.

There may be all kinds of things going on, situations are all different, and so the ideal response from the microphone is going to change along with that. The native response of the mic is very rarely the ideal response for the end recording, and that's why careful EQ is so useful. The best we can hope for is a good starting point which can be manipulated into what we want.

When farther away, we generally need more high-frequency boost to compensate for distance, which is what "diffuse field equalized" means - the microphone has somewhat of a high frequency boost built-in to it's native response. EQ can do the same thing afterwards, pretty much (see below). Sometimes a recording made at a distance will benefit from a low-bass boost too, but that's a different issue, and since every situation is different, there is no knowing if you'll need a boost or a cut, or what shape it should be. Generally though, when up close you'd want to start from a flatter response, and when farther away you want to start with a diffuse field type response with a bit of a high frequency boost.

Yet the exact amount is always going to vary. Some times the sound engineer is over-boosting certain frequency ranges, or doing the opposite. I guarantee I can make these mics sound muffled with zero high frequency content at all with EQ, just like I can make them shrill and over-bright sounding, or sound just right like I want it to sound.

Again, the native response of the microphone is simply the starting point. I'd suggest you try boosting and cutting by ear, first with a broad wide curve (low 'Q') to get things sounding close to right, and then maybe use an additional narrow (higher 'Q') filter to sweep around and find then cut whatever narrow range are hearing as being "overemphasized". I bet it is probably a rather narrow resonance range that is bothering your ear, and not so much the broad, shelf-like response. Work by ear to get things sounding natural and correct, rather than working by eye to try and dial in a curve which specifically reverses the native mic response curve in search of flatness.

Working that way, a diffuse-equalized native response with a somewhat boosted treble can have another advantage with miniature mics which often don't have a particularly low self-noise floor. If the native response imparts increased sensitivity at high frequencies, which causes you to cut some high-frequencies to get things sounding right, you will also be reducing the level of high frequency noise and hiss from the microphone itself at the same time, essentially making the background of the recording sound quieter than it would have if the mic had a flatter response. Likewise, if you simply do not need to boost that range as much as you would otherwise, you won't be boosting the noise as much either.

It's nice to have a native response which is close to what we want to start with, but far more interested in a response which I can manipulate to whatever I want easily without problems, and that usually means a relatively smooth response without narrow resonances, even if it is not particularly flat.

I find the response using the high-boost / long-grids too peaked to be useful for me, and instead always use the short-grids, adjusting EQ as necessary. If I need another +5dB in the treble to compensate for distance (or for whatever) I'll use a shelf-filter or a peaking filter with a low Q. It's been a long time since I tried using the long grids, and I may now be able to EQ around their higher Q peak sucessfully, but I suspect that would end up being more work than adjusting from the low-boost curve response which I've become very familiar with.

Forgot about that thread. Thanks for the link and the reminder. It covers the self-noise / preemphasis thing a bit more thoroughly.

When I bought my new set of 4061s here in Colorado recently they were nice enough to match them for me at no cost. They are 1/10th of 1 dB apart. This is a service that they normally do not do here in the US. They also no longer provide charts for 406x series mics unless they are sent into the Denmark plant for a fee. I was able to watch the whole process of matching as well. Pretty cool stuff.

The stereo matched kits that DPA sells can differ up to 1.5 dB apart from each other and still be considered matched FYI.